Traditional surveying may involve operators working with a theodolite and range pole. One operator generally positions the theodolite over a known point while the other operator holds the range pole at a series of points whose locations are to be determined. A target mounted on the range pole is sighted through the theodolite and accurate angular measurements are obtained. Accurate distance measurements may also be obtained using a measuring tape or any other distance measuring device. The locations of the points can be determined using the angular and distance measurements in accordance with known triangulation techniques.
In modern satellite based surveying, an operator may move about with a survey instrument that determines position information using a global navigation satellite system (GNSS). The satellite positioning system most commonly used today is the global positioning system (GPS), although others such as the global orbiting navigation system (GLONASS) are in use or under development. The operator generally moves about a site and stops at various points to record location information determined using signals transmitted by satellite sources. Correction data may be transmitted from a reference site using a telemetry system.
Cameras are often used with modern survey instruments to associate location information with image information. The combined information can be used with known photogrammetry techniques to determine three-dimensional coordinates of points. Such techniques often use two or more overlapping or adjacent images taken from different stations (e.g., different locations). Cameras can be arranged to obtain images that provide a continuous view of a scene. Many survey instruments, for example, have one or more cameras configured to obtain one or more images that provide up to a full 360° view.
The location and image information can be processed at a site using a controller or may be processed at an office remote from the site using a computer system. The image information allows for additional measurements to be obtained at any time as long as the additional points or objects are visible in the images.
As the use of location and image information becomes more widespread, techniques to utilize and view the information become increasing important. Thus, improved methods for displaying image data and locating points of interest in images are continuously desired.